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Scientia Silvae Sinicae ›› 2022, Vol. 58 ›› Issue (2): 171-181.

• Research papers •

### Effect of Extraction Treatment on Acoustic Vibration Performance of Paulownia Wood

Rui Li1,Yuanyuan Miao1,2,Xiaodong Qian1,Bin Lin1,Xianglong Jin1,Muzhi Li1,Zhenbo Liu1,2,*

1. 1. Key Laboratory of Bio-Based Material Science and Technology of Ministry of Education, Northeast Forestry University Harbin 150040
2. Engineering Research Center of Advanced Wooden Materials, Ministry of Education Harbin 150040
• Received:2021-01-18 Online:2022-02-25 Published:2022-04-26
• Contact: Zhenbo Liu

Abstract:

Objective: This study was carried out to explore the influences of extraction treatments on the acoustic vibration performance of paulownia wood used for Chinese national musical instrument, with the aims to provide a theoretical basis for the improvement of wood acoustic quality, promote the improvement of acoustic quality of Chinese musical instrument products, and alleviate the increasingly scarce situation of high-quality wood resources for musical instrument soundboards. Method: Four solvents(benzyl alcohol, deionized water, dichloromethane and absolute ethanol) were used to extract paulownia wood for 15 days. Based on the free bending vibration method, the effects of extraction treatments on the acoustic vibration performance parameters such as elastic modulus E, shear modulus G, specific dynamic elastic modulus E/ρ, logarithmic attenuation coefficient σ, acoustic impedance ω, acoustic radiation quality constant R, E/G, sound transmission speed υ, transmission parameter υ/σ and acoustic conversion efficiency υ/(σ ·ρ) were measured and analyzed. The influence mechanisms of extraction treatments on acoustic vibration performances were analyzed by microstructure observation, infrared spectroscopy(FTIR) and X-ray diffraction(XRD). Result: Acoustic performance parameters of paulownia wood were changed after extracting by deionized water, dichloromethane, benzyl alcohol and absolute ethanol. The specific dynamic elastic modulus E/ρ, acoustic radiation quality constant R and sound transmission speed υ increased by 7.67%, 11.36% and 3.75%, respectively. The improvement effect of dichloromethane extraction treatment was the best, with an increase of 13.99%, 17.28% and 6.77%, respectively. The acoustic impedance ω and logarithmic attenuation coefficient σ decreased by 3.23% and 19.42%, on average. The maximum decrease was -5.03% and -23.45%, respectively, after deionized water extraction. From the perspective of energy utilization, the acoustic conversion efficiency υ/(σ ·ρ) and transmission parameter υ/σ increase by 38.89% and 29.21%, on average. The improvement effect of dichloromethane extraction treatment was the best, with an increase of 47.66% and 35.10%, respectively. The infrared spectrum curve of paulownia wood after extraction treatment did not change significantly, but the absorption peak intensity of hydroxyl and hemicellulose decreased slightly. It could be seen from the microstructure of wood that the ducts and pits of the specimens after extraction were clearer, and the porosity of wood was retained. XRD analysis showed that the extraction treatment did not change the diffraction peak position, only affected the intensity of the diffraction peak. The relative crystallinity of paulownia wood treated with benzyl alcohol, deionized water, dichloromethane and absolute ethanol increased by 4.73%, 10.25%, 3.56% and 7.66%, respectively. The change rate of dichloromethane extraction was the largest (17.42%). Conclusion: The acoustic vibration performance of paulownia wood can be improved with extraction treatment, but the degree of improvement is different with different solvent extraction treatments. Overall, the improvement effect of dichloromethane and benzyl alcohol extraction is better. Different solvents have different improvement effects on different acoustic vibration performance indexes of wood. In the future, a combination of two or more solvent extraction can be considered to improve the acoustic vibration performance of wood.

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